Photoconductive material for electrophotography

ABSTRACT

A PHOTOCONDUCTIVE MATERIAL FOR ELECTROPHOTOGRAPHY WHICH CONSISTS ESSENTIALLY OF AN INDOLINE DERIVATIVE HAVING A RADICAL REPRESENTED BY THE FOLLOWING FORRMULA I:   1-(R2-(CH2)N-),2-((-)X-CO-CH=),3,3-DI(CH3-),5-R1-2,3-   DIHYDROINDOLE   WHEREIN R1 REPRESENTS A HYDROGEN, A HALOGEN ATOM, A LOWER ALKYL -NO2, -OR OR -COOR GROUP (R BEING A LOWER ALKYL GROUP), R2 REPRESENTS H, -OR5, -CN OR A PHENYL GROUP (R3 BEING H OR A LOWER ALKYL GROUP), N IS AN INTEGER HAVING THE VALUE OF 1-4, X REPRESENTS EITHER A SINGLE BOND OR -NH- GROUP.

United States Patent Ofiice 3,730,711 Patented May 1,1973

Int. Cl. G03g 5/06 FOR us. or. 9s--1.s 8" Claims ABSTRACT OF THE DISCIiOSURE A photoconductive material for electrophotography which consists essentially of an indoline derivative having a'radical represented by the following Formula I:

wherein R represents a hydrogen, a halogen atom, a lower alkyl --NO --OR or COOR group (R being a lower alkyl group); R represents H, OR CN or a phenyl group (R being H or a lower alkyl group); n is an integer having the value of l-4; X represents either a single bond or NH- group. a

CH3 CH3 onoox where, R is a hydrogen, a halogen atom, a lower alkyl, -NO OR or COOR group (R being a lower alkyl group): R is H, --R CN or a phenyl group (R being H or a lower alkyl group): n is an'integer having" the value of 1-4; X is either a single bond or -NH.

Of the 2-substituted-methylene indolinederivative in V accordancewith this invention,--compounds-represented by the following general Formula II or III are particularly effective as photoconductive materials :for, electropho tography:

CH3 CH3 -CHCOXR3 N Qn ' CH3 CH5 CH: CH:

R1 1 CHCOXRiXCOCH- III N (CH2), EM:

where, R, R R R n and X have the meanings given in general Formula I, R, is an alkyl, an alkenyl, an aryl, or an aralkyl group; and R is a divalent linking radical like:

(Y being any substitute and m a positive integer).

The lower alkyl group represents an alkyl group having 1-4 carbon atoms.

The foregoing compounds have new structures entirely different from those of the conventionally known organic photoconductive materials for use in electrophotography. Of the compounds which are represented by the generic Formula II or III,' those in which X is -NH-- are synthesized by the reaction Z-methylene indoline derivatives with isocyanates (refer to 0, Mumm, Ber 72 2107 (1939)) and further those in which X is a single bond are synthesized by the reaction of 2-methylene indoline derivatives with chlorides of acids (refer to Piccinini; Gazg, chim, ital, 28 (i), 187 (1898)).

By utilizing the above synthetic method, a number of compounds are synthesized through combination of various Z-methylene indoline derivatives with various isocyanates, diisocyanates, monobasic chlorides of acids, and dibasic chlorides of acids. In this invention, it has been found that many compounds thus prepared are useful as organic photoconductive materials for electrophotography. Now, the method of synthesis is described in further detail. For example, 5 g. of 1,3,3-trimethyl-2- methylene indoline and 3.4 g. of phenyl isocyanate are mixed in toluene and heated at C. for 20 minutes. The reaction solution is concentrated under reduced pressure and the remaining viscous substance is crystallized with addition of petroleum ether. When the crystallization product is recrystallized with a mixed liquid of xylene and ligroin, there is obtained a white crystalline product having a melting point of 137 C. This is a compound of the generic formula wherein R is H, R is H, n is 1, X is -NH- and R is phenyl group.

As another example, 3.4 g. of l,3,3-trimethyl-2-methylene indoline and 2.8 g. of benzoyl chloride are mixed in 30 ml. of toluene and heated at 80 C. for one hour. Thereafter, the reaction mixture is combined with 2 g. of

-triethylamine and heated at 80 C. for two hours additionally. Hydrochloride triethylamine which elutes in the fol-n1 oiicrystals; is s epar ated by filtration and the remaining's'ln'tioii isconc'eii'trated"under"re'duced 'pressure to permit separation of crystalsllwhen the crystalline product is recrystallized with methanol, there is obtained a phenyl group. ,1

By following the same procedure, there were synthesized yellow crystalline product having a melting point of 134 5 the compounds which are shown in the table.

1 TABLE 1 l (CIIzh-Bg l i h Melting n point 1 of the l 1 7 4 i reaction j l a t 1,; 2 product Number R1 R1 7L Isouyanate or acid chloride C.)

. 1 OOCl OCN CH2 NCO 4 H H 1 v 189 5 H 11 1 CH1 NCO 241 -OH7COC1 1 CH- -QHOQC 1 10...; on; 11 1 I i 16a 1 1 'NGO v 12 60113 11 1 0 14000 I, 131 13 OOH; n 1- i .7 131 14 000021-15 H 1 on; N00 103 16 11 or: a (3113 @1100 x 1 N00 1' 7 LC 17 11 a 1 I I Nco i 1s H H I To put a compoundthus preparing to use as amaterial for electrophotography, the compound is dissolvedtogether with a highly ins-ulative, resinous film-forming binder in an organic solvent capable of dissolving them, and the spreading solution consequently obtained is spread on a base having a relatively high electroconductivity and allowed to dry to. form a film and serve as a sensitive layer. Further, the said spreading solution may be combined with a plasitcizer and asensitizer for the purpose of improving the film behavior and increasing the sensitivity decisively. As resinous film forming binders usable in this case, there may be cited styrene-butadiene copolymer, polystyrene, chlorinated rubber, polyvinyl chloride, vinyl chloride/vinyl acetate copolymer, polyvinylidene chloride, nitrocellulose, polyvinyl acetate, polyvinyl acetal, polyvinyl ether, silicone resin, methacrylic resin, acrylic resin, phenol resin, alkyd resin, urea/ aldehyde. resin, etc. As electroconductive bases, it is desirable to use metal plate, paper treated so as to acquire electroconductivity, and plastic film. The plasticizers usable include chlorinated biphenyl, chlorinated paraffin, phosphate type plasticizers, and phthalate type plasticizers. As sensitizers, those which are known commonly are useful, including tetracyanoethylene, tetracyanodimethane, chloranil, naphthoquinone, anthraquinone, methylene blue, crystal violet, malachite green, etc.

It is desirable that, through combination of these materials, the sensitive layer is deposited to a, dry thickness of 2-20,u. on the electroconductive base. When the organic photoconductive component accounts for more than-% by weight all of the film composition, theproduct is found to exhibit satisfactory properties from the electrophotographic point of view.

The sensitive layer thus obtained is charged uniformly I,

by means of corona discharge, exposed to light projected through a given image, and developed by either cascade developing process or liquid developing process according to the method commonly used for electrophotog:

The invention is now described in further detail by referring to preferred embodiments. This invention is not limited to such embodiments.

EXAMPLE 1 One-half (0.5) g. of Compound No. 1 given in Table 1 and 20 cc. of 10% benzene solution of polystyrene were mixed homogeneously. The resultants solution was spread to a dry film thickness of 5p. on a base of aluminum plate to obtain a sensitive layer. After drying of the solvent, the sensitive layer was positively charged in a dark place. With a film containing a positive image placed thereon, the sensitive layer was exposed through the film to a highvoltage mercury bulb (made by Toshiba, SHL-lOO) placed at a distance of 30 cm. above for about '8 seconds. When it was developed with a developing agent containing a negatively charged toner (such as developing agent for Xerox 914), there was obtained a positive image. When the layer was placed in the atmosphere of trichloroethylene, the image was fixed to give rise to a clear positive image.

EXAMPLE 2 When Compound No. 2 given in Table 1 was treated in entirely the same manner as in Example 1, there was obtained a clear positive image.

EXAMPLE 3 A clear positive image was obtained by treating Compound No. 3 given in Table 1 in entirely the same manner as in Example 1.

One-half (0.5) g. of Compound No. 5 given in Table l was dissolved in 5 cc.'of dimethyl: formaldehyde, and the resultant solution was mixed homogeneously with 20 cc. of 10% benzene solution of polystyrene. The final solution was spread to a dry thickness of 5 1. on an aluminum plate to form a sensitive layer. 0n drying of the solvent, the said sensitive layer was charged positively in a dark place. With a positive imagefilm placed on top thereof, the layer was exposed through the film to a high' voltage mercury lamp placed at a distance of 30 cm. above for about 3 seconds. Through the steps of developing and fixing, the layer afforded a clear image. In this example, when the spread material was placed in a drier at C. immediately after spreading, the film surface became transparent.*When it was maintained at room temperature for sometime and then dried, the film was deprived of transparency and there was obtained a sensitive layer having a purely white film surface. In spite of such difference in transparency, electrophotographic properties were the same for both types.

EXAMPLE 5 styrene; The final-solution 'was spread to a dry film thickness of 5 1. on an aluminum plate to form a sensitive layer. After drying of the solvent, the said sensitive layer was charged positively in a dark place. With a positive image film placed on top thereof, the sensitive layer was exposed through the film to a high-voltage mercury bulb placed at a distance of 30 cm. above for a second. Through the steps of developing and fixing, there was obtained a clear positive image.

What is claimed is:

1. Apho'toconductive element for electrophotography comprising an indoline derivative selected [from the group consisting of CH3 CH3 /CHCOXRa; and 2)n CH3 CH3 CH3 CH3 RF" R1 l =OHOCXR4XCOCH N N (113m) ($11.).

where, R is a hydrogen, a halogen atom, a lower alkyl, -N0 -OR or -COOR group (R being a lower alkyl group); R is H, -OR -CN or a phenyl group (R being H or a lower alkyl group); n is an integer having the value of 1-4; X is either a single bond or -NH--; R is an alkyl, an alkenyl, an aryl, or an aralkyl group;

and R is a divalent linking radical selected from the 6. The photoco'nductive material as claimed in claim 1 group consisting of: wherein the indoline derivative is: v v

Q, --cm mm), CH3 CH3 Y i nd 5 a (moo-Q N Q Ha where Y is an alkyl and m a Positive integer; said indoline 7. The hotoconductive material as claimed in claim 1 derivative being mixed with an electrically insulating res- Where the mdohne del'lvatlve 1S: inous, film-forming binder applied as a layer to an electrically conductive base and containing said indoline deriva- 5 tive by more than 10 percent by weight of said layer.

2. A photoconductive element as in claim 1 where said layer has a thickness of 2 to microns on said electri- CHCONH NHCOCH cally conductive base. N

3. A photoconductive element as in claim 1 where said 20 I H I mixture contains a sensitizer and a plasticizer. C a

4. The photoconductive material as claimed in claim 1 Where the indolille dfifivative is 8. The photoconductive material as claimed in claim 1 CH; CH: where the indoline derivative is:

on CH3 2 CH3 CH3 -CHGONH I y \N CHOONH(OHz)s-NHOOCH 4311a N N 5. The photoconductlve material as claimed in claim 1 where the indoline derivative is: CH3

CHa CH: CHa CH3 3 cnc ONH-QCHzQ-NHCOCH References Cited UNITED STATES PATENTS 3,287,114 11/1966 Hoegl 961.5 XR

OTHER REFERENCES 0. Mumm: Ber 72, 2107 (1939). Piccinini: Gazg, chim, ital, 28 (i), 189-196 (1898).

GEORGE F. LESMES, Primary Examiner R. MILLER, Assistant Examiner US. Cl. X.R. 

